1. Field of the Invention
The present invention relates to sport shoes (athletic shoes). More particularly, the invention relates to sport shoes in which a sole composed of a synthetic resin can easily be bonded to a shoe upper composed of natural or artificial leather and, as a result, the steps of manufacturing the shoe can be simplified.
2. Description of the Prior Art
The soles of sport shoes for use in playing soccer, football, baseball, golf, other athletic sports and the like, are commonly made of synthetic resins such as polyvinyl chloride resins, ethylenevinyl acetate copolymer resins, polyamide resins, polyurethane resins and polycarbonate resins, instead of the leather and rubber soles that were used in the past, because the synthetic resins have excellent properties such as a low specific gravity, a low water-absorbing property, good durability and high resistance to wear and abrasion.
However, soles made of those synthetic resins do not bond to a shoe upper composed of leather sufficiently strongly and they are inferior to conventional shoe soles made of leather or rubber in this point. Accordingly, peeling often occurs between the synthetic resin sole and the shoe upper during use. Although polyamide resins are most preferred for making the soles of sport shoes because they are lightweight and tough and a good fixation thereof to the female, internally threaded, receivers of calk or spike assemblies can be obtained, they are especially poor in the bondability thereof to a shoe upper composed of natural or artificial leather and there is not available an adhesive that provides completely effective bonding. Therefore, the bond between a polyamide resin shoe sole and a leather shoe upper is usually reinforced by nailing or sewing at the present. However, the appearance of the shoe is adversely affected by using such reinforcements, the time required for making the shoes is lengthened and the manufacturing process is complicated because of the need to perform such reinforcing steps.